Mycobacteriophage L5 infection of Mycobacterium bovis BCG: implications for phage genetics in the slow-growing mycobacteria

Mycobacteriophage L5 is a well-characterized temperate phage that forms stable lysogens in Mycobacterium smegmatis . The host range of L5 is, however, unclear because previous reports suggested that it does not infect slow-growing mycobacteria such as Mycobacterium tuberculosis and bacille Calmette-Guérin (BCG). Moreover, luciferase reporter phage derivatives of L5 failed to produce light from BCG, suggesting that infection is blocked at or before the stage of DNA injection. In this study, we demonstrate that L5 infection of slow growing mycobacteria specifically requires a high concentration of Ca²⁺, conditions that differs from those required for infection of M. smegmatis by L5 and for infection of BCG by the closely related phage D29. In addition, we show that there are specific genetic determinants of L5 that confer the ability to infect slow growing mycobacteria, without altering infection of M. smegmatis . These observations extend the use of phage L5 for the diagnosis and analysis of tuberculosis and other mycobacterial diseases.     

Pulsed field gel electrophoresis of representatives of Mycobacterium tuberculosis and Mycobacterium bovis BCG strains

Abstract Using field inversion gel electrophoresis (FIGE), different Mycobacterium tuberculosis strains, such as phage prototypes, exhibit different DNA restriction patterns which are easy to compare. Virulent and avirulent variants of M. tuberculosis H37, as well as daughter strains of M. bovis BCG, display characteristic DNA profiles. BCG strains isolated from suppurative adenitis following vaccination of French patients showed patterns identical to the BCG Pasteur strain used for vaccination. These results demonstrate that FIGE of DNA restriction fragments generated by Dra I represents a suitable technique for the analysis of mycobacteria at a genomic level. The Dra I profiles allow the differentiation and precise identification of the BCG Pasteur, Glaxo, Russian and Japanese strains.     

Modification of the mycobacteriophage Ms6 attP core allows the integration of multiple vectors into different tRNAala T-loops in slow- and fast-growing mycobacteria

Background  

Mycobacteriophage Ms6 integrates into Mycobacterium smegmatis and M. bovis BCG chromosome at the 3' end of tRNA^ala genes. Homologous recombination occurs between the phage attP core and the attB site located in the T-loop. Integration-proficient vectors derived from Ms6 are useful genetic tools, but their insertion sites in the BCG chromosome remain poorly defined. The primary objective of this study was to identify Ms6 target genes in M. smegmatis and BCG. We then aimed to modify the attP site in Ms6-derived vectors, to switch integration to other tRNA^ala loci. This provided the basis for the development of recombinant M. bovis BCG strains expressing several reporter genes inserted into different tRNA^ala genes.     

Integration and excision of the Mycobacterium tuberculosis prophage-like element,phiRv1

The genomes of Mycobacterium tuberculosis H37Rv and CDC1551 each contain two prophage-like elements, phiRv1 and phiRv2. The phiRv1 element is not only absent from Mycobacterium bovis BCG but is in different locations within the two sequenced M. tuberculosis genomes; in both cases phiRv1 is inserted into a REP13E12 repeated sequence, which presumably contains the bacterial attachment site, attB, for phiRv1. Although phiRv1 is probably too small to encode infectious phage particles, it may nevertheless have an active integration/excision system and be capable of moving from one chromosomal position to another. We show here that the M. tuberculosis H37Rv phiRv1 element does indeed encode an active site-specific recombination system in which an integrase of the serine recombinase family (Rv1586c) catalyses integration and excision and a small, basic phiRv1-encoded protein (Rv1584c) controls the directionality of re-combination. Integration-proficient plasmid vectors derived from phiRv1 efficiently transform BCG, can utilize four of the seven REP13E12 sites present in BCG as attachment sites, and can occupy more than one site simultaneously.     

The secreted antigens of Mycobacterium tuberculosis and their relationship to those recognized by the available antibodies

Proteins secreted by strains of Mycobacterium tuberculosis during short-term, zinc-sufficient batch culture were identified in order to define antigens likely to be relevant to the pathogenesis of human disease. [35S]Methionine-labelled proteins in supernatants of 4-7 d cultures were separated by PAGE under both denaturing and non-denaturing conditions, and the position of labelled material was determined. Secreted protein patterns of M. tuberculosis were quite similar to those of Bacillus Calmette-Guérin (BCG) but differed by the absence of the 46 kDa dimeric protein specific to BCG and by the presence in large amounts of a 23 kDa protein which, when denatured, gave 13 kDa subunits. This 13 kDa subunit protein constituted up to 20% of secreted proteins in classical strains of M. tuberculosis of phage type B but was not detected in phage type I strains from South India. This may be relevant to the different pathogenicity of these strains. Western blot analysis showed that antigens defined in supernatants of short-term (3 d) cultures of M. tuberculosis constituted a small subset of those seen in supernatants of organisms cultured for longer periods. One of the secreted proteins has the interesting property of binding to fibronectin. The available monoclonal antibodies and antisera have been used to identify lines on immunoblots corresponding to the secreted/released antigens of M. tuberculosis. The present findings suggest that there are major secreted antigens to which antibodies do not yet appear to have been produced experimentally.     

Identification of expression signals of the mycobacteriophages Bxb1, L1 and TM4 using the Escherichia-Mycobacterium shuttle plasmids pYUB75 and pYUB76 designed to create translational fusions to the lacZ gene.

Mycobacterial expression signals were cloned using specially constructed gene fusion shuttle plasmid probes carrying a truncated Escherichia coli lacZ (beta-galactosidase) gene which lacked a promoter, a ribosome binding site, and an ATG start codon. Libraries of mycobacteriophage Bxb1, L1 and TM4 DNAs were constructed, and introduced by electroporation into Mycobacterium smegmatis and the 'bacille Calmette-Guérin' (BCG). Clones carrying mycobacterial expression sequences were detected by their blue colour or characteristic fluorescence when plated on media containing chromogenic or fluorogenic substrates. Varying degrees of beta-galactosidase expression were observed, and one Bxb1 expression signal was identified where beta-galactosidase expression is repressed in phage lysogens.     

Superinfection immunity of mycobacteriophage L5: applications for genetic transformation of mycobacteria

Mycobacteriophage L5 is a temperate phage of the mycobacteria that forms stable lysogens in Mycobacterium smegmatis. We show here that the 183-amino-acid product of L5 gene 71 confers immunity to L5 superinfection, is required for maintenance of the lysogenic state and contains a helix-turn-helix DNA-binding motif—properties associated with repressors of temperate phages. We have utilized these observations to demonstrate the use of L5 gene 71 as a selectable marker for genetic transformation of the mycobacteria. Significantly, the use of L5 gene 71 as a selectable gene avoids the requirement for antibiotic-resistance genes providing an important tool for manipulation of the pathogens Mycobacterium tuberculosis and Mycobacterium avium, and for the construction of recombinant BCG vaccines.     

Effect of repeat dose of BCG vaccination on humoral response in mice model

BCG is the only vaccine presently available against tuberculosis but it is estimated to prevent only 5% of the all potentially vaccine-preventable deaths due to Tuberculosis. Keeping these in view the present study has been undertaken to evaluate the efficacy of BCG and the effect of repeat dose of BCG on antimycobacterial humoral response in mouse model. To improve BCG immunogenicity, specific anti-mycobacterial immune responses (anti-BCG titre and total IgG level) were evaluated in mouse model using boost immunization protocols with the BCG vaccine. Mice induced with a repeat dose of BCG showed an increased anti mycobacterial humoral response, which gradually declined few weeks after single dose of BCG administration. The results suggest improved efficacy of BCG vaccine by giving repeat dose of BCG that can enhance the level of immunoprotection against tuberculosis as opposed to a single BCG dose.     

Adjuvanticity effect of sodium alginate on subcutaneously injected BCG in BALB/c mice

Bacillus Calmette-Guerin (BCG) is the only available vaccine against tuberculosis. The research for an improved vaccine is currently a very active field of investigation. In the present study, adjuvanticity effect of sterile sodium alginate on subcutaneous BCG vaccination in BALB/c mice was investigated. Mice were vaccinated subcutaneously with BCG plus alginate and the immune response and protective effect were compared to those of mice vaccinated with BCG alone by the same route. Proliferative and delayed-type hypersensitivity responses, IFN-γ, specific anti-mycobacterium total IgG, IgG1 and IgG2a production were significantly higher in mice immunized subcutaneously with BCG plus alginate in comparison with results of mice immunized with BCG alone. Following systemic infection with BCG, mice vaccinated with BCG plus alginate had lower mean bacterial count compared to those vaccinated with BCG alone. The immune responses induced by subcutaneous administration of BCG plus alginate were significantly better than the responses induced by standard BCG vaccination.     

Highlights of the 3rd international BCG symposium: 100th anniversary of the first administration of BCG

2021 was the year of the 100th anniversary of the first administration of the Bacillus Calmette-Guérin (BCG) to a human being. It was the start of a long journey of the world's most widely used vaccine and the oldest vaccine still in use. More than 4 billion children have been vaccinated with BCG for protection against tuberculosis. However, over the years it became apparent that BCG also has beneficial non-specific effects. As such, it provides protection against various heterologous infectious and non-infectious diseases and is used to treat non-muscle-invasive bladder cancer. As BCG was developed at the Institut Pasteur de Lille by Albert Calmette and Camille Guérin, the Institute has celebrated this important anniversary with an international scientific symposium on all aspects of BCG, held from November 17 to 19, 2021 at the Institut Pasteur de Lille. It covered BCG against tuberculosis and described novel vaccine approaches, the effect of BCG against heterologous infections, including BCG and COVID-19, the effect of BCG against cancer, and BCG against auto-immune and inflammatory diseases. To discuss these areas, the symposium gathered close to 200 participants from all five continents, 2/3 on-line. This article presents the highlights of this 3rd International Symposium on BCG.     

Immunogenicity of orally-delivered lipid-formulated BCG vaccines and protection against Mycobacterium tuberculosis infection

Lipid formulations containing BCG strains Danish 1331 or Moreau (Rio de Janeiro) were trialled as oral vaccines in rodent models. In mice, oral-delivery of either strain resulted in BCG colonisation of the alimentary tract lymphatics and induction of gamma-interferon responses. In guinea pigs, both strains provided pulmonary protection against Mycobacterium tuberculosis aerosol challenge, as shown by significantly reduced bacterial loads and lung:body weight ratios. Lipid-formulated BCG provided superior protection against M. tuberculosis over unformulated orally-delivered BCG (Moreau), and equivalent protection to sub-cutaneous BCG (Danish) immunisation. Oral-delivery of lipid-formulated BCG may offer a practical alternative to parenteral-route BCG vaccination.     

mpt64-卡介苗重组疫苗的构建、免疫原性及抗结核作用

通过基因工程重组技术将结核分枝杆菌保护性抗原MPT64的编码基因与穿梭质粒载体pYUB295重组,采用电穿孔技术将重组质粒导入到卡介苗中,应用聚合酶链反应(PCR)扩增、聚丙烯酰胺凝胶电泳(PAGE)对mpt64-卡介苗重组疫苗鉴定:成功地构建了MPT64基因pYUB295重组质粒,MPT64蛋白在卡介苗中能分泌表达....     

Formulation of a mmaA4 gene deletion mutant of Mycobacterium bovis BCG in cationic liposomes significantly enhances protection against tuberculosis

A new vaccination strategy is urgently needed for improved control of the global tuberculosis (TB) epidemic. Using a mouse aerosol Mycobacterium tuberculosis challenge model, we investigated the protective efficacy of a mmaA4 gene deletion mutant of Mycobacterium bovis BCG (ΔmmaA4BCG) formulated in dimethyl dioctadecyl ammonium bromide (DDA) - D(+) trehalose 6,6 dibenenate (TDB) (DDA/TDB) adjuvant. In previous studies, deletion of the mmaA4 gene was shown to reduce the suppression of IL-12 production often seen after mycobacterial infections. While the non-adjuvanted ΔmmaA4BCG strain did not protect mice substantially better than conventional BCG against a tuberculous challenge in four protection experiments, the protective responses induced by the ΔmmaA4BCG vaccine formulated in DDA/TDB adjuvant was consistently increased relative to nonadjuvanted BCG controls. Furthermore, the ΔmmaA4BCG-DDA/TDB vaccine induced significantly higher frequencies of multifunctional (MFT) CD4 T cells expressing both IFNγ and TNFα (double positive) or IFNγ, TNFα and IL-2 (triple positive) than CD4 T cells derived from mice vaccinated with BCG. These MFT cells were characterized by having higher IFNγ and TNFα median fluorescence intensity (MFI) values than monofunctional CD4 T cells. Interestingly, both BCG/adjuvant and ΔmmaA4BCG/adjuvant formulations induced significantly higher frequencies of CD4 T cells expressing TNFα and IL-2 than nonadjuvanted BCG or ΔmmaA4BCG vaccines indicating that BCG/adjuvant mixtures may be more effective at inducing central memory T cells. Importantly, when either conventional BCG or the mutant were formulated in adjuvant and administered to SCID mice or immunocompromised mice depleted of IFNγ, significantly lower vaccine-derived mycobacterial CFU were detected relative to immunodeficient mice injected with non-adjuvanted BCG. Overall, these data suggest that immunization with the ΔmmaA4BCG/adjuvant formulation may be an effective, safe, and relatively inexpensive alternative to vaccination with conventional BCG.     

In vivo persistence and protective efficacy of the bacille Calmette Guerin vaccine overexpressing the HspX latency antigen

New strategies to control infection with Mycobacterium tuberculosis, the causative agent of tuberculosis, are urgently required, particularly in areas where acquired immunodeficiencies are prevalent. In this report we have determined if modification of the current tuberculosis vaccine, Mycobacterium bovis BCG, to constitutively express the mycobacterial HspX latency antigen altered its protective effect against challenge with virulent M. tuberculosis. Overexpression of M. tuberculosis HspX in BCG caused reduced growth in aerated cultures compared to control BCG, but growth under limited oxygen availability was not markedly altered. Upon infection of mice, BCG:HspX displayed tissue-specific attenuation compared to control BCG, with reduced growth within the lung and liver but not the spleen. Both BCG:HspX and control BCG protected mice against aerosol M. tuberculosis challenge to a similar extent, however, immunodeficient mice infected with BCG:HspX survived significantly longer than mice infected with the control BCG strain. Therefore, altering the in vivo persistence of BCG by overexpression of HspX may be one important step towards developing a new tuberculosis vaccine with an improved safety profile and suitable protective efficacy against M. tuberculosis infection.     

Effects of BCG (Bacillus Calmette–Guérin) Vaccines on Immune Responses in Mice

The effects of killed and living BCG on antibody production against hamster erythrocytes (HRBC) and the 2, 4, 6-trinitrophenyl (TNP) group were studied in SL mice. Killed and living BCG, each in doses of 0.008 mg, 0.08 mg, 0.8 mg and 8 mg per mouse, were intravenously inoculated 7 days prior to primary immunization with HRBC. Secondary immunization was carried out 28 days later with TNP-HRBC. Anti-HRBC and anti-TNP antibodies were estimated by a hemagglutination test. The results showed that pretreatment with killed or living BCG enhanced the antibody production against both HRBC and TNP. Comparing the effects of these two BCG preparations, it was noted that killed BCG augmented the anti-HRBC antibody production more effectively than living BCG. In regard to the anti-TNP antibody production, living BCG exhibited a greater augmenting effect than killed BCG. This difference in the modes of action of killed and living BCG was remarkable when two groups given 8 mg of killed and living BCG were compared. In addition, it was shown that living BCG at a dose as high as 8 mg was able to augment the anti-TNP antibody production, even in the absence of preceding immunization with HRBC.     

Effect of nonspecific immune stimulation with BCG and polidin on the Ehrlich ascites tumor growth

Investigations were performed to study: 1) the antitumor effect of BCG pretreatment on the development of Ehrlich ascites tumor in mice; 2) the effect of BCG administration in relation to the period of time before tumor inoculation and the dose levels used, and 3) the antitumor effect of an associated pretreatment of BCG and Polidin on the development of Ehrlich ascites tumor. BCG administered prior to Ehrlich ascites tumor inoculation have a protective effect evidenced by a delay in tumor development, a prolonged survival of the tumor host and, in some cases, even inhibition of tumor growth. The effect of BCG was highly dependent on 1) the dose and the time of administration of BCG and) 2 the combined pretreatment of BCG and Polidin.     

Cryptic plasmids of Mycobacterium avium: Tn552 to the rescue

Plasmids have been described in almost all bacterial species analysed and have proven to be essential genetic tools. In many bacteria these extrachromosomal DNAs are cryptic with no known markers or function, which makes their characterization and genetic exploitation extremely difficult. Here we describe a system that will allow the rescue of any circular DNA (plasmid or phage) using an in vitro transposition system to deliver both a selectable marker (kanamycin) and an Escherichia coli plasmid origin of replication. In this study, we demonstrate the rescue of four cryptic plasmids from the opportunistic pathogen Mycobacterium avium. To evaluate the host range of the rescued plasmids, we have examined their ability to be propagated in Mycobacterium smegmatis and Mycobacterium bovis BCG, and their compatibility with other mycobacterial plasmids. In addition, we use a library of transposon insertions to sequence one plasmid, pVT2, and to begin a genetic analysis of plasmid genes. Using this approach, we identified a putative conjugative relaxase, suggesting this myco-bacterial plasmid is transferable, and three genes required for plasmid establishment and replication.     

BCG对乳腺癌细胞增殖和凋亡的影响

目的从细胞增殖和凋亡两方面观察BCG对乳腺癌细胞MDA—MB-231的抑制作用。方法用MTT法检测BCG作用后MDA—MB-231细胞的增殖能力,采用TUNEL法检测凋亡。结果BCG能明显降低MDA-MB-231细胞的增殖代谢活性而抑制其增殖。TUNEL法染色显示BCG可显著增加凋亡细胞。结论BCG不仅能显著抑制MDA—MB-231细胞增殖,还能有效诱导其凋亡。     

A new side effect of BCG immunotherapy — BCG-induced arthritis in man

Summary Ten of 159 patients showed arthritic symptoms during the course of BCG immunotherapy for advanced cancer. The arthritic symptoms occurring after BCG injections had the following characteristics: (1) The incidence of arthritis was closely correlated with the host immunologic responsiveness to BCG; (2) These symptoms usually occurred 1–5 months after the first BCG injection (7/10); (3) The arthritic symptoms usually started with morning stiffness (9/10), which was followed by acute inflammatory signs in the affected joints. They gradually subsided in response to treatment with nonsteroid antiinflammatory drugs, but were not completely cured while the effectiveness of BCG continued; (4) The symptoms were aggravated by additional BCG injections (8/10). (5) This form of arthritis could be differentiated from rheumatoid arthritis, tuberculous, or purulent arthritis by its clinical course and by roentgenograms of the affected joints. It is thought to be induced by the adjuvant effect of BCG, and is a new side effect of BCG immunotherapy.     

Growth of sarcoma 180 in normal and splenectomized BALB/c mice immunized with BCG

An evaluation was made on the growth of Sarcoma 180 (S 180) in normal and splenectomized BALB/c mice which had been immunized 40 days before the tumor challenge with BCG, either intradermally or in diffusion chambers placed in the peritoneal cavity. Immunization with intradermal BCG did not modify the growth of subcutaneous S 180, whereas it provided significant protection when the tumor was inoculated with BCG. Previous treatment with BCG in diffusion chambers had no effect on the development of S 180, but significantly decreased the percentage of survival of mice inoculated with S 180 mixed with BCG, as compared to the homologous group immunized with intradermal BCG. Splenectomy performed before the challenge with S 180, enabled 56% of mice lacking previous immunization to survive and increased this percentage to 100% when the tumor was inoculated mixed with BCG. As for splenectomized mice immunized with BCG within diffusion chambers and challenged with S 180, there was 90% of survival and 69% in those challenged with S 180 mixed with BCG. These results would suggest that the action of BCG on the growth of S 180 differs according to whether the mycobacteria are in direct contact with the host or exert their effect by means of soluble antigens capable of passing through the millipore filter of the diffusion chambers. These effects would be conditioned by the immunological state of the host.